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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * A RTC driver for the Simtek STK17TA8
4 *
5 * By Thomas Hommel <[email protected]>
6 *
7 * Based on the DS1553 driver from
8 * Atsushi Nemoto <[email protected]>
9 */
10
11#include <linux/bcd.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/gfp.h>
15#include <linux/delay.h>
16#include <linux/jiffies.h>
17#include <linux/interrupt.h>
18#include <linux/rtc.h>
19#include <linux/platform_device.h>
20#include <linux/io.h>
21#include <linux/module.h>
22
23#define RTC_REG_SIZE 0x20000
24#define RTC_OFFSET 0x1fff0
25
26#define RTC_FLAGS (RTC_OFFSET + 0)
27#define RTC_CENTURY (RTC_OFFSET + 1)
28#define RTC_SECONDS_ALARM (RTC_OFFSET + 2)
29#define RTC_MINUTES_ALARM (RTC_OFFSET + 3)
30#define RTC_HOURS_ALARM (RTC_OFFSET + 4)
31#define RTC_DATE_ALARM (RTC_OFFSET + 5)
32#define RTC_INTERRUPTS (RTC_OFFSET + 6)
33#define RTC_WATCHDOG (RTC_OFFSET + 7)
34#define RTC_CALIBRATION (RTC_OFFSET + 8)
35#define RTC_SECONDS (RTC_OFFSET + 9)
36#define RTC_MINUTES (RTC_OFFSET + 10)
37#define RTC_HOURS (RTC_OFFSET + 11)
38#define RTC_DAY (RTC_OFFSET + 12)
39#define RTC_DATE (RTC_OFFSET + 13)
40#define RTC_MONTH (RTC_OFFSET + 14)
41#define RTC_YEAR (RTC_OFFSET + 15)
42
43#define RTC_SECONDS_MASK 0x7f
44#define RTC_DAY_MASK 0x07
45#define RTC_CAL_MASK 0x3f
46
47/* Bits in the Calibration register */
48#define RTC_STOP 0x80
49
50/* Bits in the Flags register */
51#define RTC_FLAGS_AF 0x40
52#define RTC_FLAGS_PF 0x20
53#define RTC_WRITE 0x02
54#define RTC_READ 0x01
55
56/* Bits in the Interrupts register */
57#define RTC_INTS_AIE 0x40
58
59struct rtc_plat_data {
60 struct rtc_device *rtc;
61 void __iomem *ioaddr;
62 unsigned long last_jiffies;
63 int irq;
64 unsigned int irqen;
65 int alrm_sec;
66 int alrm_min;
67 int alrm_hour;
68 int alrm_mday;
69 spinlock_t lock;
70};
71
72static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
73{
74 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
75 void __iomem *ioaddr = pdata->ioaddr;
76 u8 flags;
77
78 flags = readb(pdata->ioaddr + RTC_FLAGS);
79 writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
80
81 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
82 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
83 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
84 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
85 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
86 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
87 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
88 writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
89
90 writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
91 return 0;
92}
93
94static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
95{
96 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
97 void __iomem *ioaddr = pdata->ioaddr;
98 unsigned int year, month, day, hour, minute, second, week;
99 unsigned int century;
100 u8 flags;
101
102 /* give enough time to update RTC in case of continuous read */
103 if (pdata->last_jiffies == jiffies)
104 msleep(1);
105 pdata->last_jiffies = jiffies;
106
107 flags = readb(pdata->ioaddr + RTC_FLAGS);
108 writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
109 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
110 minute = readb(ioaddr + RTC_MINUTES);
111 hour = readb(ioaddr + RTC_HOURS);
112 day = readb(ioaddr + RTC_DATE);
113 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
114 month = readb(ioaddr + RTC_MONTH);
115 year = readb(ioaddr + RTC_YEAR);
116 century = readb(ioaddr + RTC_CENTURY);
117 writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
118 tm->tm_sec = bcd2bin(second);
119 tm->tm_min = bcd2bin(minute);
120 tm->tm_hour = bcd2bin(hour);
121 tm->tm_mday = bcd2bin(day);
122 tm->tm_wday = bcd2bin(week);
123 tm->tm_mon = bcd2bin(month) - 1;
124 /* year is 1900 + tm->tm_year */
125 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
126
127 return 0;
128}
129
130static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
131{
132 void __iomem *ioaddr = pdata->ioaddr;
133 unsigned long irqflags;
134 u8 flags;
135
136 spin_lock_irqsave(&pdata->lock, irqflags);
137
138 flags = readb(ioaddr + RTC_FLAGS);
139 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
140
141 writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
142 0x80 : bin2bcd(pdata->alrm_mday),
143 ioaddr + RTC_DATE_ALARM);
144 writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
145 0x80 : bin2bcd(pdata->alrm_hour),
146 ioaddr + RTC_HOURS_ALARM);
147 writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
148 0x80 : bin2bcd(pdata->alrm_min),
149 ioaddr + RTC_MINUTES_ALARM);
150 writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
151 0x80 : bin2bcd(pdata->alrm_sec),
152 ioaddr + RTC_SECONDS_ALARM);
153 writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
154 readb(ioaddr + RTC_FLAGS); /* clear interrupts */
155 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
156 spin_unlock_irqrestore(&pdata->lock, irqflags);
157}
158
159static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
160{
161 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
162
163 if (pdata->irq <= 0)
164 return -EINVAL;
165 pdata->alrm_mday = alrm->time.tm_mday;
166 pdata->alrm_hour = alrm->time.tm_hour;
167 pdata->alrm_min = alrm->time.tm_min;
168 pdata->alrm_sec = alrm->time.tm_sec;
169 if (alrm->enabled)
170 pdata->irqen |= RTC_AF;
171 stk17ta8_rtc_update_alarm(pdata);
172 return 0;
173}
174
175static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
176{
177 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
178
179 if (pdata->irq <= 0)
180 return -EINVAL;
181 alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
182 alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
183 alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
184 alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
185 alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
186 return 0;
187}
188
189static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
190{
191 struct platform_device *pdev = dev_id;
192 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
193 void __iomem *ioaddr = pdata->ioaddr;
194 unsigned long events = 0;
195
196 spin_lock(&pdata->lock);
197 /* read and clear interrupt */
198 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
199 events = RTC_IRQF;
200 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
201 events |= RTC_UF;
202 else
203 events |= RTC_AF;
204 rtc_update_irq(pdata->rtc, 1, events);
205 }
206 spin_unlock(&pdata->lock);
207 return events ? IRQ_HANDLED : IRQ_NONE;
208}
209
210static int stk17ta8_rtc_alarm_irq_enable(struct device *dev,
211 unsigned int enabled)
212{
213 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
214
215 if (pdata->irq <= 0)
216 return -EINVAL;
217 if (enabled)
218 pdata->irqen |= RTC_AF;
219 else
220 pdata->irqen &= ~RTC_AF;
221 stk17ta8_rtc_update_alarm(pdata);
222 return 0;
223}
224
225static const struct rtc_class_ops stk17ta8_rtc_ops = {
226 .read_time = stk17ta8_rtc_read_time,
227 .set_time = stk17ta8_rtc_set_time,
228 .read_alarm = stk17ta8_rtc_read_alarm,
229 .set_alarm = stk17ta8_rtc_set_alarm,
230 .alarm_irq_enable = stk17ta8_rtc_alarm_irq_enable,
231};
232
233static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val,
234 size_t bytes)
235{
236 struct rtc_plat_data *pdata = priv;
237 void __iomem *ioaddr = pdata->ioaddr;
238 u8 *buf = val;
239
240 for (; bytes; bytes--)
241 *buf++ = readb(ioaddr + pos++);
242 return 0;
243}
244
245static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val,
246 size_t bytes)
247{
248 struct rtc_plat_data *pdata = priv;
249 void __iomem *ioaddr = pdata->ioaddr;
250 u8 *buf = val;
251
252 for (; bytes; bytes--)
253 writeb(*buf++, ioaddr + pos++);
254 return 0;
255}
256
257static int stk17ta8_rtc_probe(struct platform_device *pdev)
258{
259 unsigned int cal;
260 unsigned int flags;
261 struct rtc_plat_data *pdata;
262 void __iomem *ioaddr;
263 int ret = 0;
264 struct nvmem_config nvmem_cfg = {
265 .name = "stk17ta8_nvram",
266 .word_size = 1,
267 .stride = 1,
268 .size = RTC_OFFSET,
269 .reg_read = stk17ta8_nvram_read,
270 .reg_write = stk17ta8_nvram_write,
271 };
272
273 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
274 if (!pdata)
275 return -ENOMEM;
276
277 ioaddr = devm_platform_ioremap_resource(pdev, 0);
278 if (IS_ERR(ioaddr))
279 return PTR_ERR(ioaddr);
280 pdata->ioaddr = ioaddr;
281 pdata->irq = platform_get_irq(pdev, 0);
282
283 /* turn RTC on if it was not on */
284 cal = readb(ioaddr + RTC_CALIBRATION);
285 if (cal & RTC_STOP) {
286 cal &= RTC_CAL_MASK;
287 flags = readb(ioaddr + RTC_FLAGS);
288 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
289 writeb(cal, ioaddr + RTC_CALIBRATION);
290 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
291 }
292 if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
293 dev_warn(&pdev->dev, "voltage-low detected.\n");
294
295 spin_lock_init(&pdata->lock);
296 pdata->last_jiffies = jiffies;
297 platform_set_drvdata(pdev, pdata);
298 if (pdata->irq > 0) {
299 writeb(0, ioaddr + RTC_INTERRUPTS);
300 if (devm_request_irq(&pdev->dev, pdata->irq,
301 stk17ta8_rtc_interrupt,
302 IRQF_SHARED,
303 pdev->name, pdev) < 0) {
304 dev_warn(&pdev->dev, "interrupt not available.\n");
305 pdata->irq = 0;
306 }
307 }
308
309 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
310 if (IS_ERR(pdata->rtc))
311 return PTR_ERR(pdata->rtc);
312
313 pdata->rtc->ops = &stk17ta8_rtc_ops;
314
315 nvmem_cfg.priv = pdata;
316 ret = devm_rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
317 if (ret)
318 return ret;
319
320 return devm_rtc_register_device(pdata->rtc);
321}
322
323/* work with hotplug and coldplug */
324MODULE_ALIAS("platform:stk17ta8");
325
326static struct platform_driver stk17ta8_rtc_driver = {
327 .probe = stk17ta8_rtc_probe,
328 .driver = {
329 .name = "stk17ta8",
330 },
331};
332
333module_platform_driver(stk17ta8_rtc_driver);
334
335MODULE_AUTHOR("Thomas Hommel <[email protected]>");
336MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
337MODULE_LICENSE("GPL");